I think my fuel pump is on it's way out. Can I just put one of the in-line pumps on the car instead of dropping the tank? If I have to drop the tank anyway then I'll just put another in tank pump in but, does a higher volume pump do anything for a car with fairly minimal mods? I'll include my signiture at the bottom, it shows all of my "mods". It's pretty long, I got bitched at about it the other day. I've got a 1990 Iroc with 305 TPI 5 speed. I'd like to know what volume pump I should go with. Any suggestions? Any particular manufacturer? Thanks guys!

 

How do you know the pump is going out? Have you checked the pressure at idle? WOT? If the pressure is holding good then you shouldn't need to replace it. If you do install a new pump, it won't help you in the hp unless you have the fuel system maxed out and require the bigger pump which I doubt you do. Also, if you do decide to install a new pump, you might as well throw in a larger one, as it will help if you have some big mods planned in the future.

 

How about installing an inline pump instead of dropping the tank? Can I do that? The other question I sort of knew about, I just didn't know if a higher pressure from the pump helped the Pressure regulator or not.

 

TTT

 

Installing an inline pump may cure the problem, but thats really a "band-aid" fix if your pump is in fact "on its way out".
Chance are, the pump thats in there has been there many years, hell it may be the original, which would mean the fuel sock attached to it is probably crammed full of crap, so in order to replace it, you much drop the tank anyway.
When I changed mine, car had about 40k miles on it, and I couldn't believe all the garbage stuck in the sock.
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Do it right the first time, drop the tank, replace the pump and sock with a Walbro 307 pump, plently of flow and power for your mods and room to grow, if you want bigger, go with a Walbro 340.

 

2QUIK6, Thank YOU!! That's just the information I was looking for! I do in fact still have the original pump still in the tank. It's got 105, 000 miles worth of crap in it like you said, though the engine has about 8,000 on the rebuild. I totally forgot about the in-tank filter. That's why I love this place, you can get so many perspectives on a problem. Is the Walbro 307 a stock replacement pump? Do you know about how many liters per hour that pump puts out? One last question, does fuel pump output play a factor in the pressure in the fuel rails? What I'm asking is, with a higher volume pump do I need to turn the AFPR up as much to get the same pressure and atomization I would get with a stock pump? Does all this make sense? Thanks, and Merry Christmas!

 

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No, the Walbro is not a stock replacement, it flows much higher than a stock replacement, it looks and mounts just like the stock one on the intake hanger.
For comparison of flow ratings, check here:
http://gnttype.org/techarea/fuelsyst...ectiondoc.html
http://gnttype.org/techarea/fuelsystem/pmprate.html
And general Fuel pump info / flow:
http://gnttype.org/techarea/fuelsystem/fuelpage.html
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I know most of the above pages is in reference to GN stuff, but the stock EFI fuel pumps are all the same for the most part.
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As far as pressure, by installing a higher flowing pump, your Fuel pressure may go up several psi, so you'll need to adjust it back to your normal setting at idle. With that same setting, you should see a few more psi at WOT, which is good if your old pump was weak.
Remember, your AFPR is just a spring, when you put a pump in there that flows alot more fuel, its going to cause the AFPR to have to open more to allow more fuel to pass thru it to maintain pressure, so you will have to adjust the tension/pressure in that spring to allow it to maintain proper fuel pressure.
The more a pump can flow, the better it can maintain FP at WOT.

Hope that helps, theres a ton of fuel information on those pages listed above.